Information distribution system and program for the same

ABSTRACT

An information distribution system described herein is capable of securely storing digitized personal information in an encrypted state in a storage section and securely transferring/disclosing the stored digitized information only to a particular third person via a network. Communication of the information is securely performed in the encrypted state between information terminals connected to the communication network. An information terminal which has created information encrypts the original information by a common key generated upon communication and stores the information in a secure storage of one of the information terminals connected to the communication network while maintaining the encrypted state. Further, the system creates a mechanism for authenticating a person having a particular authority for viewing the encrypted information and index information having an encrypted common key and link information indicating the location of the information for supply to a user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 13/770,281 filed Feb. 19, 2013, which is a continuation applicationof U.S. application Ser. No. 12/810,658 filed Jun. 25, 2010, which is aNational Phase of PCT/JP08/73556 filed Dec. 25, 2008, and claimspriority to Japanese Patent Application No. 2007-337732 filed Dec. 27,2007. The entire contents of each of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to an information distribution system anda program for realizing the information distribution system. Moreparticularly, the present invention relates to an informationdistribution system excellent in security and information distributionperformance between a server and a client or between a plurality ofclient information terminals, such as peer-to-peer terminals, via theInternet network, and a program for realizing the informationdistribution system.

BACKGROUND ART

In recent years, networks such as the Internet have become indispensableinfrastructure of society, and systems for sophisticatedly usinginformation are built on the networks. On the other hand, just likeother properties, information can be considered as assets owned byindividuals or corporations. If important information is leaked over anetwork through which the information diffuses instantly, irrevocableloss will be caused. Innumerable information leakage problems in such amanner actually occur in reality.

However, if strictly keeping information secret in order to preventleakage, it will cause inconvenience in information exchange andinformation utilization between kind collaborators, such as sharingmedical information between medical experts for cooperation purpose.

In order to securely deliver information and yet sophisticatedly useinformation, it is necessary to develop an information distributionsystem enabling both the “security of information” and the “freedom ofinformation exchange”.

Such a system, which can securely hold information and securely transferthe information to a required place, is configured by a secure storagesystem and a secure transport system.

However, under the current circumstances, although an encrypted storagesystem and an encrypted transport system are individually arranged andsecurity thereof is each guaranteed, it is undeniable that there is adangerous area between the storage system and the transport system. Inother words, there exist cases such as where data taken from theencrypted file is transmitted after being decrypted, where data receivedby encryption communication is then stored in plaintext, and the like.All these are elements which may lead to information leakage.

Further, access authentication for accessing the storage (file) systemand opposite party authentication for performing communication aretypically separately managed. Further, management of theseauthentications is performed by an expert on the center side, and theclient (the user) who actually owns the information can not designate aperson to access the information on his (or her) terminal side and onhis (or her) own will.

As described above, there are two problems. The first problem lies insecurity of information transmission. With the conventional method inwhich the information is encrypted and transmitted, and then theencrypted information is decrypted at the destination to obtain theoriginal information, it is impossible to completely guarantee security.The second problem lies in freedom of information transmission. For thesake of “security”, management of access to the information is performedby an administrator on the server side, and therefore the actual ownerof the information can not freely handle the information and freelydisclose the information to a trusted third person.

As an encryption technology to solve the first problem, there is astorage technology which has an encryption storage function. Theencryption storage function is responsible for transmitting electronicdata (such as image, character and the like) in an encrypted state, andstoring the data in a storage section in the encrypted state.

Herein, an encryption key for performing encryption is managed by theuser who sends the information. Thus, the encryption key of the user whosends the information has to be used to decrypt the encrypted data.Thus, only the owner of the encryption key (i.e., the user who sends theinformation) can encrypt his (or her) electronic data, and decrypt theencrypted data.

However, since the user who sends the information obviously will nevergive his (or her) encryption key to any other person, the difficultproblem is still outstanding when the user wants to securely distributethe encrypted electronic data to a particular user other than himself(or herself).

As to the second problem, for example, when performing communicationbetween a head office and a branch office via the Internet, highsecurity has to be guaranteed. To serve this purpose, a technique isproposed in which a private key is provided to the server on the headoffice side, and a public key corresponding to the private key of thehead office is provided to each client on the branch office side (seePatent Document 1).

According to the technique disclosed in Patent Document 1, a common keyis generated on the branch office side (i.e., the client side). Further,the generated common key is encrypted using the public key andtransmitted to the server side (i.e., the head office side). The servercan obtain the common key generated on the client side by decrypting thereceived information with its own private key.

[Patent Document 1] Japanese Unexamined Patent Application PublicationNo. 2002-305513

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

The art disclosed in Patent Document 1 is a system for performinginformation encryption and decryption by both the server of the headoffice and the client of the branch office. Although security ofcommunication is guaranteed, there is a danger that the data isdecrypted on the server side so that the data can be referenced byanyone. If the data is not once decrypted, the data can not betransferred from the server to the other client. Further, the client whoowns the information can not designate a client to use the information(i.e., a client to whom the owner want to transfer the information). Inother words, the system is provided with no mechanism for storingpersonal information in an encrypted state and providing the storedinformation to the server and the other clients in the encrypted state.The information can not be distributed if the administrator on theserver side is not interposed.

As described above, it is a reality that, in the current technology,when personal information is created as electronic data, there is notechnique established for allowing the owner of the personal informationto securely store his (or her) electronic data in a storage section byhimself (or herself), and securely disclose the stored electronic datato a trusted third person by himself (or herself) via a network.

In view of the aforesaid problems, it is an object of the presentinvention to provide an information distribution system enabling a userto securely store his (or her) personal information, which is created aselectronic data, in a storage section in an encrypted state, andsecurely transmit the stored electronic data to a particular trustedthird person via a network, and a program for the informationdistribution system.

Means for Solving the Problems

To achieve the aforesaid object, an information distribution systemaccording to an aspect of the present invention is adapted to distributeinformation between a plurality of information terminals connected to acommunication network.

First, at least one information terminal of the plurality of informationterminals comprises: a section adapted to store a public key and aprivate key necessary to encrypt the common key; a common key generatingsection adapted to generate a common key for performing encryptioncommunication between itself and another information terminal via thecommunication network; an original information encrypting sectionadapted to encrypt original information owned by any one of theplurality of information terminals based on the common key; a common keyencrypting section adapted to encrypt the common key with the publickey.

Further, the one information terminal comprises: a common key extractingsection adapted to extract the encrypted common key with the privatekey; a decryption processing section adapted to decrypt encryptedinformation of encrypted original information encrypted by the oneinformation terminal based on the extracted common key; an encryptedsignature generating section adapted to generate an encrypted signatureusing the private key.

On the other hand, at least one information terminal of the otherinformation terminals of the plurality of information terminals has: asecure storage including an original information storing section adaptedto store the encrypted original information encrypted by the oneinformation terminal in the encrypted state, and a secure transport corehaving a program for performing encryption communication of theinformation transmitted/received via the communication network installedtherein.

Further, the at least one information terminal of the plurality ofinformation terminals connected to the communication network comprises:an authorized terminal authenticating section adapted to authenticate anauthorized information terminal of the plurality of informationterminals that is authorized to view the encrypted original informationby the information terminal that owns the encrypted originalinformation; a link information generating section adapted to generatelink information for linking encrypted information of the common key tothe encrypted information of the original information; an indexinformation generating section adapted to generate index information fordisclosing the link information and the encrypted information of thecommon key and the original information to the one information terminalof the plurality of information terminals and the authorized informationterminal; and a secure transport core having a program for performingencryption communication of the information transmitted/received via thecommunication network installed therein.

Although each information terminal has an encryption processing blockaccording to the aforesaid configuration, the present invention alsoincludes a configuration in which an external box is interposed in theconnection portion between each information terminal and the Internet,and the external box is provided with a function for performingencryption processing. Further, the present invention also includes aconfiguration in which a proxy information terminal (a proxy server) forperforming encryption processing is provided.

Incidentally, in such cases, the encryption processing is executed by aprogram installed in each information terminal, the external box, or theproxy server.

Advantages of the Invention

According to the present invention, it is possible to perform encryptioncommunication between a client (a user) terminal and a server, orbetween client terminals via the Internet communication network.Further, it is possible for a user (an owner) who owns the originalinformation (for example, an image x) to only allow a third person whois authorized to view or hold the information (for example, the image x)of the owner to reference or hold the information. In other words, it ispossible for the owner to decide by himself (or herself) whether or notto allow the third person to decrypt and reference the stored encryptedimage x, and therefore it is possible to provide an informationdistribution system having extremely high security.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual rendering showing an information distributionsystem according to a first embodiment of the present invention;

FIG. 2 is a block diagram showing the configuration of the informationdistribution system according to the first embodiment of the presentinvention;

FIG. 3 is a schematic block diagram for explaining encryption processingand decryption processing in the case where the information distributionsystem according to the first embodiment of the present invention isused as a medical information distribution system;

FIG. 4 is a flowchart showing a part of the flow of the processing ofthe medical information distribution system according to the firstembodiment shown in FIG. 3, until the step of storing encrypted image;

FIG. 5 is a flowchart showing another part of the flow of the processingof the medical information distribution system according to the firstembodiment shown in FIG. 3, until the step of referencing and verifyingthe encrypted image;

FIG. 6 is a conceptual rendering showing an information distributionsystem according to a second embodiment of the present invention;

FIG. 7 is a block diagram explaining the function of external boxes ofthe information distribution system according to the second embodimentof the present invention;

FIG. 8 is a conceptual rendering showing the schematic configuration ofan information distribution system according to a third embodiment ofthe present invention; and

FIG. 9 is a block diagram explaining the function of a proxy server (asecure transport server) of the information distribution systemaccording to the third embodiment of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION

First, a secure transport management function used in an informationdistribution system of the present invention will be explained beforedescribing the embodiments of the present invention. The securetransport function, which is the substantial part of the presentinvention, constitutes a secure transport system (STS) which isconfigured by organically integrating a secure transport core (STC) anda secure storage system (SSS).

Herein, the secure transport core (STC) is, for example, softwarearranged on a transport layer for achieving end-to-end secure transportand has extension corresponding to various packet contents. In otherwords, in the secure transport core (STC), since all accesses toinformation (such as registering, referencing and changing information)are authenticated, and all communications are performed by encryptedsecure transport, security of communication can be guaranteed. Further,since the original information is recorded remaining in the encryptedstate as it was when performing secure transport, without beingdecrypted, the original information can not be stolen even by theadministrator of the information server computer. Thus, it is possibleto completely prevent information from being stolen.

Further, in the secure storage system (SSS), only addition and registerof information are allowed, deletion of information is not allowed.Further, a signature of the creator of the information is added to theoriginal information, which makes it possible to detect whether theinformation is falsified. Thus, the recorded original information isstored without being changed by any person. Further, since the changeand/or addition added to the original information are recorded as neworiginal information, falsification can be prevented. Furthermore, sincethe original information is stored in a state clearly defined by theowner, only the owner or a valid user authorized by the owner can usethe stored information (i.e., the owner or a valid user can use thestored information).

In other words, the encrypted original information is stored in thecenter in a state where only the owner of the registered data and thevalid user authorized by the owner can use the information. This featureleads to complete prevention of sniff/steal of the original information.Incidentally, in the secure storage system (SSS), only accumulation ofinformation is possible, and the accumulated information will not bedeleted until a period defined by the owner has elapsed. Thus, there isno concern that important information might be deleted by mistake.

Further, since register, update and reference of the information arerecorded as history, the history record can be provided upon asubmission request from the owner of the registered data or from thevalid user authorized by the owner. Incidentally, the history record isalso prevented from being falsified and deleted by the same method asthat of the original information.

Further, since the owner and the valid user authorized by the owner areauthenticated by a public key authentication method, it is also possibleto prevent spoofing. Further, reference to the original information isalso performed by secure transport, and when making copy, theinformation is record in the encrypted state as it was when performingtransport. Incidentally, it is also possible to allow the owner todetermine whether to authorize the valid user to only reference theoriginal information, or to authorize the valid user to even make acopy, according to necessity.

Further, the owner of information may entrust another entity or a thirdperson (a proxy) with the authority to issue the aforesaid authorizationto the user. Further, the entrusted proxy may authorize the authorityowned only by the owner to a particular user, within a range defined bythe owner. Thus, “availability” of the information distribution systemaccording to the present invention can be improved.

Further, in the secure storage system (SSS), when there is an actionsuch as reference, addition and/or the like performed on the originalinformation, the time of the action, the person who performs the action,and the content of the action will be recorded as log data. Since suchinformation is stored in a manner in which the data can not be changedby any person, it is possible to accurately trace the information later.

Further, in the secure transport system (STS), processes such as securetransport, encrypted record and the like are executed with no need forthe user to pay any attention or to make any change to application,except for actions such as authentication, to which the user has to payattention. This property is called “application transparency”.

Further, in the case where the information terminals are provided withno secure transport system (STS) function, a method can be used in whichan external box having STS function installed thereto is added to thenetwork on the side to which the information terminal is connected, sothat it seems as if each information terminal is provided with STSfunction. This method can be achieved by employing a so-called gateway(GW) device, and thereby availability of the system of the presentinvention can be improved. The details of this method will be describedlater with reference to FIGS. 6 and 7.

Also, it is considerable that a proxy server serving as a proxy forproviding STS function is provided, so that even in the case where theclient terminal has no secure transport system (STS) function, STS canbe available by using the proxy server. Thus, “availability” of thesystem according to the present invention can be improved. The detailsof this method will be described later with reference to FIGS. 8 and 9.

First Embodiment

The configuration and operation of an information distribution systemaccording to a first embodiment (also referred to as “presentembodiment” hereinafter) of the present invention will be describedbelow with reference to FIGS. 1 to 5. Incidentally, although the presentembodiment is described based on an example in which encryptioncommunication is performed between a client terminal and a server in adata center and information processing is performed in both the clientterminal and the server, obviously the same processing may also beperformed between peer-to-peer client terminals. Herein, the clientterminal and the server are collectively called “information processingterminal”.

As shown in FIG. 1, in the information distribution system according tothe present embodiment, a client terminal (a standard personal computer)having web browser display function and a data center computer 11functioning as a server computer on the data center side are connectedwith each other though the Internet 21, which is a kind of communicationnetwork.

The data center computer 11 includes a web server 12 and a securestorage server group 13.

In the present embodiment, a driver 3 is installed on the clientterminal 2 and a driver 14 is installed on the data center computer 11,the driver 3 and the driver 14 being each provided with function of thesecure transport core, which is to be described later.

Next, basic configuration of the information distribution systemaccording to the first embodiment of the present invention will bedescribed below with reference to FIG. 2.

FIG. 2 is a functional block diagram showing the function of theinformation terminal 2 and the data center computer 11, which areconfigured to achieve the secure transport system of the presentembodiment.

As shown in FIG. 2, the information terminal 2 on the side of the clientincludes functions of an application adapted to store and referenceinformation, a secure transport program, and a maintenance application,which are to be described later.

Herein, the application adapted to store and reference informationincludes a web browser, and is adapted to display and reference, forexample, an image using the web browser.

Further, the secure transport program includes the secure transport coreand a secure transport extension/authentication function. The securetransport core has a secure transport function for performing mutualauthentication, encryption key exchange and encryption/decryption withthe encryption key on the information transmitted/received between theinformation terminal 2 and the other information terminals (includingthe data center server 11) through the Internet 21.

Further, the secure transport core has a function for performingflexible grouping to allow or deny connection between the informationterminals according to the type of TCP/IP based application, and forediting and processing the data stream of the information. Further,since a function for selecting extension corresponding to theapplication is provided depending on the content of the packet, securitycan be achieved without modifying the existing application.

Further, the secure transport extension/authentication function has thefollowing four functions. The first function enables the creator of theinformation to encrypt a common key for encrypting the information to bestored using a public key of the owner of the information so that onlythe owner can reference the information. The second function enables theowner of the information to take out the common key, which was used whenthe creator of the information performed the encryption, to decrypt theinformation (data), and transfer the decrypted data to the application.Further, the third function enables the owner of the information toencrypt the common key with a public key of a third person trusted bythe owner so as to allow the trusted third person to reference theinformation. The fourth function enables the user of the information(i.e., the trusted third person) to take out the common key, which wasused when the owner of the information performed the encryption, todecrypt the information (data), and transfer the decrypted data to theapplication.

As shown in FIG. 2, the secure transport extension/authenticationfunction has a role to transparently provide a service function of thesecure transport core (STC) and the secure storage system (SSS) withrespect to the information transport application. Herein, as mentionedabove, the term “to transparently provide” means processing is executedwith no need for the user to pay any attention or to make any change toapplication, except for actions such as authentication, to which theuser has to pay attention.

Further, the secure transport extension/authentication function alsoprovides general functions such as signing, compressing,encrypting/decrypting, decompressing and verifying the data stream ofmain application protocols such as HTTP (Hyper Text Transfer Protocol),FTP (File Transfer Protocol), SMTP (Send Mail Transfer Protocol), POP3(Post Office Protocol version 3) and the like. By using the securetransport extension/authentication function, it is possible to securelymaintain or store a plurality of encryption keys, and also, it ispossible to access an agency where the private keys are archived.Further, it is possible to provide an access to a PKI (Public KeyInfrastructure) which is a system for exchanging public keys.

Further, the data center computer 11 shown in FIG. 2 includes anapplication adapted to store and reference information, a securetransport program, an encrypted storage application, and a maintenanceapplication.

The application adapted to store and reference information has afunction for communicating the encrypted information between itself andthe application of the client terminal through a web server, and storingthe encrypted information in a secure storage of the encrypted storageapplication, or enabling reference of the stored encrypted information.

Further, the secure transport program has the same function as that ofthe information terminal 2, and is adapted to perform secure transportbetween the data center computer 11 and the information terminal 2through the Internet 21. In addition to functions of the securetransport extension/authentication function of the information terminal2, the secure transport extension/authentication function of the datacenter computer 11 further has a function for adding a signature of thecreator to the encrypted original information. Thus, it is possible tomore reliably prevent falsification of information.

The encrypted storage application of the data center computer 11includes a secure storage service and a replication service. Further,the secure storage service is adapted to store information for each userin a respective one of a plurality of user-dedicated storages 16 of asecure storage 15 in the encrypted state, so that confidentiality can beprotected. Further, the signature of the registrant is added, so thatvalidity of the information can be confirmed. Further, it is possible toconfirm that the information is not falsified.

Further, the secure storage service is adapted to provide theapplication on the center side with a function for storing the encryptedinformation in the user-dedicated storage 16 and referencing theinformation. At this time, all histories (logs) of register, update andreference of the information are recorded as evidence.

Further, the replication service of the encrypted storage application isadapted to automatically connect the data center 11 with a plurality ofother centers and perform information synchronization of the securestorage. As a result, the information stored in one center is alsostored in other centers simultaneously or with a predetermined time lag.Thus, even if the information storage of one center is damaged, theinformation can be obtained from the other centers, and thereforeinformation can be prevented from being completely lost. This functionensures availability.

Incidentally, the maintenance application secure transport managementservice of the information terminal 2 and the data center computer 11 isadapted to manage the public keys of both the owner and the trustedthird person. Further, the maintenance application is adapted to createand distribute the secure transport program to the information terminalthat first uses the system, and the maintenance application is alsoadapted to perform license management of the program, change the settingof the program, monitor operation, collect log, and the like.

Further, the encrypted storage application is configured so that theencryption key is stored in the user-dedicated storage 16 in a statewhere the encryption key can only be used by the owner of the registeredinformation and the “valid user” authorized by the owner (i.e., thetrusted third person). Further, register, update and reference of theregistered information are recorded as history, and the history can beprovided upon a submission request from the owner of the registeredinformation and from the “valid user” authorized by the owner.

Incidentally, in the encrypted storage application, amount of algorithmsfor analyzing and using the encryption key is great, and therefore it isextremely difficult for a third person to sniff/steal the data. Further,the registered information can not be changed, and will not be deleteduntil a predetermined period has elapsed. Thus, the information havingbe changed is accumulated as new information.

As described above, in the secure transport system (STS) of the presentembodiment, by performing the encrypted secure transport, the originalinformation is stored in the secure storage 15 owned by the originalinformation server. Thus, it is safe to say that sniff and falsificationof information can be almost completely prevented.

Further, since the original information is stored remaining in theencrypted state as it was when performing secure transport, withoutbeing decrypted, the original information is archived in a state wherethe original information can not be stolen even by the administrator ofthe server computer. Further, since the signature of the creator isadded to the original information, the archived original information cannot be changed except by the creator who signed the originalinformation. Incidentally, even if the change and/or addition is addedto the original information by the creator, since the change and/oraddition is recorded as new original information, falsification of theoriginal information can be prevented.

Herein, as an example of a mechanism for controlling reference oforiginal information, a reference index will be described below. Asdescribed later, the original information can be decrypted andreferenced only through the reference index. The reference indexincludes a link L to the original information and an encryption key ofthe original information encrypted with the public key of a referenceperson (a person who is allowed to reference the data). Thus, thereference person can decrypt the reference index and the originalinformation with his (or her) private key, and read the decryptedoriginal information.

At first, only the owner of the original information has the referenceindex. Then, the owner of the original information obtains the publickey of a reference person who is authorized to reference the originalinformation, creates a reference index for the reference person, anddelivers the created reference index to the reference person so that thereference person can reference the original information. In other words,only the owner can add the reference index. With such a configuration,it is possible to retain the ownership of the owner and authenticate thereference person.

Next, the processing of the information distribution system according tothe embodiment of the present invention (the present embodiment) will bedescribed below with reference to the block diagram of FIG. 3 and theflowcharts of FIGS. 4 and 5.

FIG. 3 is made to describe the information distribution system accordingto the present embodiment in detail. In FIG. 3, an entity 2A is thecreator who creates the original information x. In the case of themedical information distribution system of the present embodiment, theentity 2A is a physical examination agency A0 who creates the data.Further, an entity 2B is the owner of the original information, and inthe medical information distribution system of the present embodiment,the entity 2B is a patient B0. An entity 2C is the user who can read theoriginal information x, and in the present embodiment, the entity 2C isa doctor C0 who is a trusted third person. These entities 2A, 2B and 2Care connected to the data center computer 11 and perform the followingprocessing using the secure storage 15 of the data center computer 11.

First, the entity 2A (i.e., the physical examination agency) creates theimage x, as the original information owned by the entity 2B (i.e., thepatient), and stores the created image x in an original informationdatabase (DB). Further, an encryption key (k) is generated by the securetransport core of the terminal of the entity 2A, and the image x isencrypted by the encryption key (k) and archived. Thereafter,information exchange is performed between the terminals or between theterminal and the center based on the generated encryption key (k).Incidentally, the entity 2A (i.e., the physical examination agency)registers the image x (i.e., the original information), and at the sametime registers that the owner of the image x is the entity 2B (i.e., thepatient). In other words, the entity 2A registers that the ownership ofthe image x belongs to the entity 2B (i.e., the patient).

It is needless to say that, when performing communication, the image x(i.e., the original information) is communicated in an encrypted state,the image x remains in the encrypted state even when being stored in thesecure storage 15 of the data center computer 11. Thus, the image x cannot be decrypted even by the owner of the server (i.e., the center) ifthe owner of the server does not know the encryption key (k). Further,the data registered in the secure storage 15 of the data center computer11 is unique, and the data can not be falsified by anyone. In otherwords, it is possible for the entity 2B (i.e., the patient), the ownerof the data, to only authorize a trusted third person, such as theentity 2C (i.e., the doctor) who is a valid user authorized by theowner, to decrypt the data.

Next, the details of the operation of the information distributionsystem shown in FIG. 3 will be described below with reference to theflowcharts of FIGS. 4 and 5. In the following description of the medicalinformation distribution system, the entity 2A (the creator of theoriginal information) is the physical examination agency A0, the entity2B (the owner of the original information) is the patient B0, the entity2C (the user of the original information) is the doctor C0, and theinformation terminals owned by the respective entities are respectivelyinformation terminals 2A, 2B and 2C.

Herein, the information terminal 2A of the physical examination agencyA0 holds a public key A, a private key a and its own ID, wherein thepublic key A and the private key previously set as a pair; and theinformation terminal 2B of the patient B0 holds a public key B, aprivate key b and its own ID. Similarly, the information terminal 2C ofthe doctor C0 holds a public key C, a private key c and its own ID.

In the secure storage service of the data center computer 11, the indexinformation is generated, and at the same time the original informationx in plaintext is compressed and encrypted, and the compressed andencrypted original information x is stored in the database. Although theoriginal information x may include the other data than the image, sincethe original information shown in FIG. 3 is the image x, hereinafter theoriginal information x and the image x are regarded as the same.

Index information E (A, k) means encrypted information obtained byencrypting the encryption key (k) with the public key A of the physicalexamination agency A0, and similarly, index information E (B, k) andindex information E (C, k) mean encrypted information obtained byencrypting the encryption key (k) respectively with the public key B andpublic key C. Further, link information L (x) is information indicatingwhereabouts of the data such as a URL, a file name or the like, andherein the link information L (x) means information indicating thelocation where the encrypted image x is stored in the secure storage 15.

The original information (image x) in plaintext is compressed andencrypted, and the encrypted image x is stored in the secure storage ofthe data center computer 11. Such information is indicated as C (k, x),which means the information of the encrypted image x encrypted with theencryption key k. In addition to the encrypted information C (k, x),also stored in the secure storage of the data center computer 11 is S(a, x), which indicates the signature (evidence) of the physicalexamination agency A0 who stores the image x.

Next, the flow of the processing of the information distribution systemaccording to the first embodiment of the present invention will bedescribed below with reference to the flowcharts of FIGS. 4 and 5.

As shown in FIG. 4, first, a digitized image x is generated with animage of the patient B0 photographed by the physical examination agencyA0 (Step S1).

At this time, the physical examination agency A0 is the “registrant ofthe data”, and the patient B0 is the “owner of the data”. The doctor C0is regarded as the “user of the data” authorized to reference the databy the patient B0 who is the “owner of the data”. Usually, the patientB0 is the person who authorizes the doctor C0 to reference the data,however the patient B0 may also entrust the physical examination agencyA0 to issue such authorization on behalf of him (or her). It is obviousthat the information distribution system may also be used in a widevariety of usages such as electronically managing the assets such asstocks and the like, instead of being limited to the medical case.

Next, generation and exchange of the encryption key with the common keyis performed (Step S2). To be specific, Step S2 is a process forperforming mutual authentication between the secure transport core onthe terminal side and the secure transport core on the center side inthe system configuration shown in FIG. 3, and generating and exchangingthe encryption key k with the common key. Here, the secure transportcore of the information terminal 2A of the physical examination agencyA0 is connected with the secure transport core on the center sidethrough the Internet 21, and the image x is transmitted to the datacenter computer 11 using the secure transport core on the center side.Further, before storing the image x in the user-dedicated storage 16, itis necessary to firstly perform mutual authentication between the securetransport core of the physical examination agency A0 and the securetransport core of the data center computer 11 and exchange theencryption key before storing the data, as describe above.

Next, the image x is compressed and encrypted using the common key kgenerated in Step S2, and the compressed and encrypted information isstored in the user-dedicated storage 16 of the data center computer 11(Step S3). Such compressed and encrypted information encrypted using theencryption key k is indicated as C (k, x). Further, in order to provethat the data is registered by the physical examination agency A0, asignature S (a, x, lax) is added as additional information of theencrypted information C (k, x). Herein “a” represents the private key ofthe physical examination agency A0, “x” represents the image, and “lax”represents the content of the signature. The content of the signature“lax” represents a profile such as, for example, the name of thephysical examination agency A0, the address of the physical examinationagency A0, data and time when the image was photographed, and the like.After Step S3 is completed, the encrypted image x is stored, as a set of[C (k, x) and S (a, x, lax)] (with signature), in the user-dedicatedstorage 16 of the data center computer 11 (Step S4).

Incidentally, when storing the data in the user-dedicated storage 16 ofthe data center computer 11, the information terminal 2A of the physicalexamination agency A0 encrypts the common key with the public key of thephysical examination agency A0. The encrypted information is regarded asE (A, k) (Step S5). Thereafter, link information L (x) linking theactual encrypted image x stored in the user-dedicated storage 16 isgenerated (Step S6). Finally, the information E (A, k) generated in StepS5 and the link information L (x) are paired, and thereby the indexinformation for the physical examination agency A0 is generated (StepS7).

At the same time, in order to disclose the secure information of theimage x to the patient B0, the information terminal 2A of the physicalexamination agency A0 encrypts the common key k with the public key B ofthe patient B0. Such encrypted information is regarded as E (B, k) (StepS8). Thereafter, similar to Steps S6 and S7, the link informationlinking the actual encrypted image x stored in the user-dedicatedstorage 16 is regarded as L (x) (Step S9), and the information E (B, k)and the link information L (x) are paired, and thereby the indexinformation for the patient B0 is generated (Step S10).

Further, the common key k is encrypted with the public key C of thedoctor C0 either at the information terminal 2A of the physicalexamination agency A0 or at the information terminal 2B of the patientB0. This processing is performed for allowing the doctor C0 to view theencrypted image x. The information of the common key k encrypted withthe public key C is regarded as E (C, k) (Step S11). Further, similar toSteps S6 and S9, the link information linking the actual encrypted imagex stored in the user-dedicated storage 16 is regarded as L (x) (StepS12). Further, the information E (C, k) generated in Step S12 and thelink information L (x) are paired, and thereby the index information forthe doctor C0 is generated (Step S13).

The flow of the processing until generating index information based onthe public keys of the information terminals of the physical examinationagency A0, the patient B0 and the doctor C0 so that the image x owned bythe patient B0 can be viewed from the respective terminals has beendescribed above description with reference to the flowchart of FIG. 4.

As secure storage service of the data center computer 11, the aforesaidindex information is respectively provided to the information terminal2A, 2B and 2C of the physical examination agency A0, the patient B0 andthe doctor C0 through the Internet 21.

Next, a case where the patient B0 references or verifies his (or her)own image x will be explained below with reference to the flowchart ofFIG. 5.

First, the information terminal 2B of the patient B0 performscommunication between itself and the data center computer 11 with thesecure transport core of itself, takes out E (B, k) of its own indexinformation [E (B, k) and L (x)], and decrypts the E (B, k) with theprivate key b, which is paired with its own public key B, to extract thecommon key k (Step S14).

Thereafter, base on the link information L (x), the information terminal2B of the patient B0 decrypts the C (k, x) of the linked encrypted imagex [C (k, x) and S (a, x, lax)] using the common key k (Step S15). Thus,the patient B0 can reference his (or her) own image x (Step S16).

Further, in order to confirm whether the image x is his (or her) ownimage, the patient B0 uses the information terminal 2B to access theimage x [C (k, x) and S (a, x, lax)] stored in the secure storage 15 ofthe data center computer 11 to acquire the signature S (a, x, lax) inthe encrypted image x. Further, based on the signature S (a, x, lax),the patient B0 verifies that the encrypted image x is identical to his(or her) own original image x, namely, verifies the validity of theencrypted image x. The validity of the image x can be confirmed bydecrypting the signature S (a, x, lax) with the public key A, which ispaired with the private key a of the physical examination agency A0(Step S17), and thereby verification of the validity is completed (StepS18).

Further, similar to the aforesaid case, the information terminal 2C ofthe doctor C0 can perform communication between itself and the datacenter computer 11, and decrypt E (C, k) of its own index information [E(C, k) and L (x)] with the private key c, which is paired with its ownpublic key C, to extract the common key k. Further, after extracting thecommon key, the doctor C0 can reference the image x of the patient B0 byaccessing the encrypted image x [E (C, k) and L (x)] linked by the linkinformation L (x) and decrypting the C (k, x) of the image x with thecommon key k.

As described above, in the information distribution system according tothe first embodiment of the present invention, the information terminal2A of the physical examination agency A0 performs compressing,encryption and encryption communication of the image from the webbrowser thereof.

In the information distribution system according to the first embodimentof the present invention, information terminals 2A to 2C each have aprogram indicated as the driver shown in FIG. 1 installed therein.Similarly, the data center computer 11 also has a program indicated asthe driver installed therein. With such a simple configuration,encryption communication between each of the information terminals 2A to2C and the data center computer 11 can be performed via the Internet 21.In such a case, only the third person authorized by either the physicalexamination agency A0 who is the registrant of the original image x orthe patient B0 who is the owner of the original image x can decrypt theencrypted image x and view the image, that is, only the doctor C0 whoowns the information terminal 2C can decrypt the encrypted image x andview the image.

Thus, the information distribution system according to the presentembodiment is an extremely secure system in which information can bereferenced and used only by the person who is authorized by either theowner or the registrant of the information.

Further, the encrypted image x (i.e., the data) registered in the securestorage 15 of the data center computer 11 is unique data withcompliance, which can not be falsified by anyone. Obviously, since theperson on side of the data center computer 11 has no private key andtherefore can not decrypt the encrypted image x and reference the image,so that the information distribution system according to the presentembodiment has extremely high security. Further, as described above, thepatient B0 can verify validity of his (or her) own image x by performingextremely simple operation.

As described above, in the present embodiment, the information terminal2 (the terminal of the client) holds the public key and the private key,and generates the common key when performing communication betweenitself and the data center computer 11 via the Internet 21.

Further, encryption processing for encrypting the original informationis performed with the generated common key, and the common key isencrypted using the public key of the other information terminal. Theindex information, which is configured by the encrypted common key andthe link information linking the encrypted information of the originalinformation, is generated in order to disclose the encrypted informationof the original information to the other information terminal.

Further, the common key is extracted using the private key, anddecryption of the encrypted information of the original information isperformed using the extracted common key. Further, communication betweenall information terminals are performed by encryption communication, andthe program for achieving the secure transport system is installed inall information terminals.

Further, the data center computer 11 has a program installed therein,wherein the program at least performs operations of: generating thecommon key, performing the encryption communication of informationtransmitted and received via a communication network, storing theencrypted information of the original information, and generating theindex information on the encrypted information of the originalinformation. Incidentally, the program installed in the data centercomputer 11 may also be reversely held by information terminal 2 on theside of the client. In other words, in the case where the programinstalled in the information terminal 2 of the client and the programinstalled in the data center computer 11 are reversely held by eachother, it is also possible to provide an application system having highsecurity.

In addition, although the aforesaid embodiment is described using anexample in which encryption communication and processing are performedbetween an information terminal (a client) and a center computer (aserver), it is obvious that, in the present embodiment, encryptioncommunication may also be performed between information terminals, suchas peer-to-peer terminals, without particularly needing a server on oneside

Second Embodiment

Next, an information distribution system according to a secondembodiment of the present invention will be described below withreference to FIGS. 6 and 7.

As shown in FIG. 6, similar to the first embodiment, the systemaccording to the second embodiment is configured by connecting theinformation terminal 2 of the client side, which has a web browserdisplay function, with the data center computer 11 through the Internetnetwork 21. Also, the system of the second embodiment is identical tothat of the first embodiment (see FIG. 1) in that the data centercomputer 11 is provided with the web server 12 and the secure storageserver group 13.

The system of the second embodiment differs from that of the firstembodiment (see FIG. 1) in that an external box 31 and an external box32 are respectively provided between the information terminal 2 of theclient side and the Internet network 21 and between the data centercomputer 11 and the Internet network 21. The external boxes have thesecure transport core, the secure transport extension/authenticationfunction and the like owned by the information terminal 2 of the firstembodiment. In other words, the external boxes 31 and 32 are used asproxy devices of the client terminal 2 and the data center computer 11shown in FIG. 1.

The external boxes 31 and 32 are typically each a dedicated device,however an appliance configured by installing dedicated software in ageneral-purpose equipment, such as a personal computer, may also be usedas each of the external boxes 31 and 32.

FIG. 7 shows internal structure of each of the external boxes 31 and 32.As shown in FIG. 7, the external boxes (the proxy devices) 31 and 32each include a secure transport core, which is adapted to performencryption/decryption with an encryption key of the informationtransmitted/received via the Internet 21, and a secure transportmanagement service function, which is a maintenance application.Further, the external boxes 31 and 32 each include a user modeapplication for managing public key, and HTTP application extension.

Further, as shown in FIG. 7, in the information distribution systemaccording to the second embodiment, the information terminal 2 (theclient) need not to be provided with a secure transport application,because the external box 31 performs this function instead. In otherwords, the information terminal 2 on the side of the client is connectedwith the external box 31, and the data center computer 11 is connectedwith the external box 32. With such a configuration, even in the casewhere the information terminal 2 and the data center computer 11 areprovided with no the secure transport application, encryptioncommunication can be performed between the information terminal 2 andthe data center computer 11 through the Internet 21.

Similar to the case of the first embodiment, in the system of the secondembodiment, by employing the system construction shown in FIG. 3, onlythe person (the user) authorized by the actual owner of the informationcan decrypt the encrypted information and reference the information,therefore it is possible to achieve a system having extremely highsecurity.

Further, similar to the system of the first embodiment, in the system ofthe second embodiment, the specific information, which is encrypted andregistered data, can not be changed. Further, since the person on sideof the data center computer 11 has no private key and therefore can notdecrypt and reference the information, so that it is possible to achievea system having extremely high security.

Furthermore, since the information distribution system according to thesecond embodiment of the present invention is simply configured byconnecting the external box 31 to the information terminal 2 andconnecting the external box 32 to the data center computer 11,encryption communication between the information terminal 2 of theclient side of and the data center computer 11 can be achieved simply byconnecting the both external boxes 31 and 32. Since the system isconfigured by adding the external boxes only, encryption communicationand processing can be relatively easily achieved even using a computersystem which has already in operation.

Third Embodiment

Next, an information distribution system according to a third embodimentof the present invention and a program therefor will be described belowwith reference to FIGS. 8 and 9.

As shown in FIG. 8, in the information distribution system according tothe third embodiment of the present invention, the information terminal2 (the client) is a usual personal computer having web browser displayfunction. In other words, the information terminal 2 is a personalcomputer such as a windows (registered trademark) personal computer, inwhich a SSL (Secure Socket Layer) for performing usual encryptioncommunication is standard-installed.

On the other hand, in the third embodiment of the present invention, inaddition to the data center computer 11 which includes the web server 12and the secure storage server group 13, a secure transport server 41 isprovided as a proxy center (a proxy server: an application serviceprovider).

The secure transport server 41 is connected so as to be able to performencryption communication with the information terminal 2 on the clientside through the Internet (the Internet network) 21 using, for example,the standard-installed SSL, and at the same time to perform encryptioncommunication with the web server 12 of the data center computer 11through the Internet 21.

Further, the secure transport server (the proxy server) 41 is configuredso as to be able to achieve authentication between the informationterminal 2 on the client side and the proxy server 41 at, for example, atransport layer located lower than the SSL application layer.

Further, a driver 3A substantially identical to the driver 3 (seeFIG. 1) of the system of the first embodiment is installed in the securetransport server 41, and similarly, a driver 14, which is equivalent tothe driver of the system of the first embodiment, is installed in theweb server 12 of the data center computer 11.

In other words, as shown in FIG. 9, the secure transport server 41 notonly has the proxy server (web+application), but also has the SSLapplication adapted to achieve encryption processing (SSL) between thedata center computer 11 and the information terminal 2.

Further, similar to the first embodiment, the secure transport server 41includes the secure transport application for performingencryption/decryption with the encryption key of thetransmitted/received information, and further includes the driver 3Awhich includes a user mode application for managing public encryptionkey and HTTP application extension.

As described above, according to the third embodiment of the presentinvention, the communication between the information terminal 2 of theclient and the secure transport server 41 via the Internet 21 isachieved by SSL encryption communication. On the other hand, thecommunication between the secure transport server 41 and the web server12 of the data center computer 11 via the Internet 21 is achieved byencryption communication identical to that of the first embodiment.

In such a case, similar to the first embodiment, by employing the systemconstruction shown in FIG. 3, only the person (the user) authorized bythe owner of the information can decrypt the encrypted information andreference the information, therefore it is possible to achieve a systemhaving high security.

Further, similar to the cases of the first and second embodiments, thespecific information (the encrypted and registered data) is stored in astate where the data can not be changed. Further, since the person onside of the data center computer 11 has no private key and therefore cannot decrypt and reference the information, it is possible to achieve asystem having extremely high security.

The following advantages can be obtained by using the informationdistribution system of the present invention and the program forachieving the system.

(a) Information is delivered by an end-to-end secure communication, andthe information is stored in the encrypted state as it was whenperforming communication.(b) Owner of the information is clearly defined, and only a trusted userauthorized by the owner can access the information.(c) Information is stored in a manner in which the information can notbe falsified, and change of the information is recorded as newinformation.(d) All accesses to information (such as reference, update, deletion andthe like) are recorded, and all these records are stored in a manner inwhich the records can not be falsified.(e) These security mechanisms are incorporated in a manner in which theuser and the application are not aware of these mechanisms.

Further, since the system according to the third embodiment of thepresent invention is an ASP (Application Service Provider) type systemin which the secure transport server 41 of the proxy center isinterposed, the system is a user-friendly system available to many userswho use the window (registered trademark) personal computer.

Although the embodiments of the present invention are described above,it should be noted that the system configurations described above areonly examples of the present invention, and the present inventionincludes various other modifications and applications without departingfrom the spirit of the claims of the present invention. Further,although the embodiments are described mainly based on an example inwhich the encryption communication is performed between a clientterminal and a server terminal, obviously the same encryptioncommunication may also be performed between information terminals suchas P2P terminals. Further, obviously the number of the informationterminals to be connected is not particularly limited.

INDUSTRIAL APPLICABILITY

The present invention can be widely applied to encryption communicationof all kind of information and decryption processing by a specifieduser, in addition to the aforesaid encryption communication of themedical image and decryption processing by a specified user.

EXPLANATION OF REFERENCE NUMERALS

-   1 information distribution system-   2 client terminal (information terminal)-   2A information terminal of creator (physical examination agency)-   2B information terminal of owner (patient)-   2C information terminal of user (doctor)-   3, 3A, 14 driver-   11 data center computer-   12 web server-   13 secure storage server group-   15 secure storage-   16 user-dedicated storage-   21 Internet-   31, 32 external box-   41 proxy center (secure transport server)-   A0 physical examination agency-   B0 patient-   C0 doctor-   A, B, C public key-   a, b, c private key-   x image

1. (canceled)
 2. An information processing apparatus, comprising: acommon key generating section to generate a common key; an originalinformation encrypting section to encrypt original information based onthe common key; a key storage section to store a public key used toencrypt the common key; a common key encrypting section to encrypt thecommon key with the public key; and a secure transport core to performencrypted communication via a communication network, wherein theencrypted common key and the encrypted original information arecommunicated via the secure transport core through the communicationnetwork.
 3. The information processing apparatus according to claim 2,wherein the communication network is a TCP/IP network.
 4. An informationprocessing apparatus, comprising: a key storage section to store aprivate key used to decrypt the common key; a common key extractingsection to extract a common key from an encrypted common key using theprivate key; a decryption processing section to decrypt encryptedinformation corresponding to the original information with the commonkey extracted from the encrypted common key; and a secure transport coreto perform encrypted communication via a communication network, whereinthe encrypted common key and the encrypted information are communicatedvia the secure transport core through the communication network.
 5. Theinformation processing apparatus according to claim 3, wherein thecommunication network is a TCP/IP network.
 6. An information processingapparatus, comprising: a secure storage section to securely storeencrypted information corresponding to original information generated atanother information processing apparatus; a link information generatingsection to generate link information associating an encrypted common keyto the encrypted information corresponding to the original information;an index information generating section to generate index information toprovide the index information and the encrypted informationcorresponding to the original information to the terminal; and a securetransport core to perform encrypted communication via a communicationnetwork.
 7. The information processing apparatus according to claim 6,further comprising: an authorized terminal authenticating section toauthenticate a terminal for access to the encrypted information based onan authorization of the another information processing apparatus.
 8. Aninformation distribution system, comprising: a plurality of informationterminals connected to a communication network, wherein at least onefirst information terminal of the plurality of information terminalsincludes a common key generating section to generate a common key, anoriginal information encrypting section to encrypt original informationbased on the common key, a key storage section to store a public keyused to encrypt the common key, a common key encrypting section toencrypt the common key with the public key, and a secure transport coreto perform encrypted communication via a communication network, whereinthe encrypted common key and the encrypted original information arecommunicated via the secure transport core through the communicationnetwork, at least one second information terminal of the plurality ofinformation terminals includes a key storage section to store a privatekey used to decrypt the common key, a common key extracting section toextract a common key from an encrypted common key using the private key,a decryption processing section to decrypt encrypted informationcorresponding to the original information with the common key extractedfrom the encrypted common key, and a secure transport core to performencrypted communication via a communication network, wherein theencrypted common key and the encrypted information are communicated viathe secure transport core through the communication network, and atleast one third information terminal of the plurality of informationterminals includes a secure storage section to securely store encryptedinformation corresponding to original information generated at anotherinformation processing apparatus, a link information generating sectionto generate link information associating an encrypted common key to theencrypted information corresponding to the original information, anindex information generating section to generate index information toprovide the index information and the encrypted informationcorresponding to the original information to the terminal, and a securetransport core to perform encrypted communication via a communicationnetwork.